The current invention relates to reservoirs for rod-like articles, particularly articles of the tobacco industry such as cigarettes or filter rods.
In the manufacture of articles of the tobacco industry it is common practice to transport the articles directly from the manufacturing equipment where such articles are made to a receiving device such as a packing machine in the case of cigarettes. The articles themselves are usually conveyed in the form of a continuous multi-layer stream of articles or xe2x80x9ccarpetxe2x80x9d moving in a direction transverse to the lengths of the articles themselves.
In common practice the depth of such carpets are 50-100 mm in height.
In addition, due to the complex nature of both the manufacturing and packaging machines used in the tobacco industry, and the high volumes of product produced and packaged per machine, it is found that if one of these machines is forced to shut down as a result of a process failure, a considerable volume of product is often left in the machine which, due to the nature of these products, often means that such left product has to be simply disposed of once the machine is restarted. Similarly, since the machines operate concurrently so as to maintain operation of both machines, it is found that if a problem is incurred in one machine such as the packaging machine, then the conveyor system between the manufacturing machine and the packaging machine will often back-up very quickly necessitating a shut-down of the corresponding machine of the pair. Thus, the problem is duplicated whereby excess product held in both machines while they are shutdown necessitates the disposal of twice as much product. For this reason, it is highly desirable that a buffer reservoir be provided to compensate for any difference in the number of products produced and the number to be packed.
There are two primary types of buffer reservoir used for this purpose, the first of which is referred to as a FIFO reservoir (first in first out) whereby such reservoirs comprise a conveyor belt for receiving product and transporting such product around a stacked loop, often in the form of a spiral, between an input station and an output station, whereby the output station is remote from the input station, such that the conveyor belt only travels in one direction so that the first product to be received in such a buffer reservoir is also the first product out, irrespective of whether or not the reservoir is maintained in continuous operation. It is common practice for such FIFO reservoirs to be of adjustable length whereby the dimensions between parallel supports of such spiralled belts are adjustable to and away from one another thereby increasing or decreasing the belt length as required to adjust capacity. In this manner if the packaging machine were to become inoperative, then by adjusting the distance between the supports of the spiral of such a FIFO reservoir, the belt length is increased and by appropriate variation of the input and output speed of the belt (the input speed may in fact be maintained constant while the output speed could be completely stopped) the excess product being fed into the reservoir is accommodated by the increase in length of the belt around the various spirals even if no product is output. Usually belts of this type are those of the type referred to as continuous endless belts which have an associated adjustment means accommodating part of the belt not carrying product, whereby a corresponding adjustment of this non product carrying length will either provide additional belt for lengthening the spiral or will accommodate belt length as the spiral is reduced in length. Example of this type of FIFO equipment is seen in European Patent No. 0738478 and WO 99/44446.
Alternatively, a second type of buffer reservoir is referred to as a FILO reservoir (first in last out). Here it is common place for the flow path of the carpet from the manufacturing machine to conventionally flow along one branch of a T-junction and to be transmitted down the main trunk of such T-junction to the packaging machine. In the event that the packaging machine is unable to cope with the volume of product from the manufacturing machine, the T junction serves to divert the product via the second branch to an input station of a, usually, spiral endless conveyor which transports the product away from this input station during the storage buffer period. Subsequently, when additional storage is no longer required, the displacement of the belt in the spiral buffer is stopped and product from the manufactured equipment is then diverted back directly to the packaging machinery. In this respect, a carpet of product is now maintained in the buffer reservoir and should there be a disruption to the manufacturing process the conveyor of the buffer reservoir can be reversed so as to transport such stored product in a reverse direction along the spiral conveyor back towards the input station so that it can be transferred to the T-junction and thus to the packaging machine. In this respect it will be appreciated that the first product to enter such a buffer reservoir will also be the last product out. An example of a FILO buffer reservoir of this type is shown in U.S. Pat. No. 5,361,888.
However, both of these standard types of reservoir equipment have been found to have certain drawbacks, whereby when the FILO equipment is used it is possible that product entered into this storage buffer could be maintained therein for a considerable period of time to the detriment of the product itself. It is necessary that the product itself is not maintained in a buffer for too long a period of time else it could suffer due to moisture in the air or otherwise become stale. As such, FILO equipment often requires periodical emptying to ensure the product does not suffer in this way and this in itself requires careful monitoring of the products stored in these buffers.
Conversely, FIFO equipment whilst avoiding the above mentioned problems of FILO equipment, necessitate both a product transportation branch and a conveyor return branch of the conveyor (the product transportation branch existing between product input station and a product output station, with the conveyor return branch extending from the product output station to the product input station) often necessitating a large volume of belt to be maintained in the conveyor return branch in order to compensate appropriate and necessary adjustment of the product conveying length of the belt. In particular, the prior art referred to above has achieved this in a rather complex manner by producing two separate belt sections such that the reservoir occupies a large area. Therefore an object of the present invention is to provide for an improved adjustable buffer reservoir which alleviates the aforementioned problems.
According to the present invention there is provided a variable capacity reservoir system for rod like articles, comprising a product input station and a product output station and having a continuous endless conveyor with an adjustable product conveying length and a complimentary adjustable conveyor take up length; it also has a conveyor adjustment means for effecting an increase or decrease of the product conveying length and complimentary decrease or increase respectively in the conveyor take up length wherein the conveyor adjustment means comprises first and second support members between which and supported by is one of the product conveying length or conveyor take up length so as to define a spiral path extending around the first and second support means; characterised in that the other of the product conveyor length or conveyor take up length is supported between the second support member and a third support member wherein the first and third support members are restrained from relative displacement towards said second support member and which second support member is displaceable relative to both the first and third support means to simultaneously effect the complimentary adjustment of the conveyor length extending between the first and second support means and the second and third support means respectively.
Preferably, at least one of the first and third support members will be secured from displacement relative to the second support member and, in one embodiment, both first and third support members are so secured from displacement. Alternatively, at least one of the first and third support members may be restrained from displacement towards the second support member by the application of a biasing force thereto in a direction away from the second support member so as to bias the at least one of the first and second support members away from the second support member. In this manner, at least one of the first and third support members will form a conveyor slack elimination device which, under the biasing force applied thereto will take up any slack in the conveyor. It is preferable that one of the first and third support members will be secured from displacement whilst the other will enjoy a biasing force to form such a conveyor slack elimination device.
Whilst it is possible for the second support member to lie offset from a plane extending between the first and third members, it is preferable that this second support member is disposed directly between the first and third support members.
It is usual that at least the first and second support members will further comprise a support means for effecting support and transmission of the spiral conveyor around the first and second support means. The support means usually define an arcuate path and preferably take the form of wheels disposed about a substantially upright or vertical axis.
The support members themselves usually comprise a cylindrical drum so that each arcuate path is disposed in a plane perpendicular to the axis of this drum, so as to preferably lie in a horizontal plane. Preferably, this reservoir system will further comprise guide means associated with at least one of an input or output of the arcuate path so as to effect displacement of the endless conveyor from a first plane to a second plane.
In a preferred form of the current invention, both the product conveying length and the conveyor take up length both extend around the second support member so as to be interleaved. This is particularly the case in the situation of a cylindrical drum.
Preferably, the first and second support members comprise parallel axis about which the spiral path extends.
In addition, it is usual that the other of the product conveying length or the conveyor take up length further defines a complimentary second spiral path around and between the second and third support members, often having the same pitch as that of the first spiral path. Whilst the pitch of both or each spiral paths may be variable around the drum, it is preferable that the spiral path pitch is constant for both spirals and often constant between each spiral path of the interleaved paths.
Alternatively, the other of the product conveying length or the conveyor take up length may define at least one pair of first and second adjacent path lengths extending between the second and third support members in opposite directions in a first plane parallel to the axis of the second support member, wherein the third support member comprises transmission means for transmitting said conveyor between said adjacent first and second path lengths in this first plane. At least one third path length may be associated with this pair of first and second path lengths, again extending between the second and third support members adjacent to and in an opposite direction to one of the first and second path lengths so as to lie in a second plane therewith, perpendicular to the axis of the second support member, wherein the second support member comprises transmission means, usually arcuate, for transmitting the conveyor between the third and one of the first and second path lengths in this second plane.
Preferably, the third support member transmission means may be independently restrained from displacement towards the second support member by the application of a biasing force thereto in a direction away from the second support member so as to bias this third support member transmission means away from the second support member. In this manner, even where the third support member is secured from displacement relative to the second support member, the transmission means on the third support member may be independently biased in this manner so as to effect a conveyor slack elimination device.
In one or more embodiments of the invention, the other of the product conveying length or conveyor take up length will define at least one serpentine path.
Preferably, the reservoir system will comprise a First In First Out system wherein the product output station is remote from the product input station such that the product conveying length extends between the input station and the output station and the conveyor take up length extends between the output station and the input station.
Alternatively, the reservoir system may comprise a reversible first in last out wherein the input station and the output station coincide at the same location, wherein the product conveying length extends between the input station and a defined stop position on the endless conveyor and the conveyor take up length extends between the stop position around the remainder of the conveyor to the product input station.
Preferably, both types of reservoir systems will comprise first and second support members standing upright so as to both lie between a first and second horizontal plane whereby the second and third support members also lie between the same first and second planes so that both the product conveying spiral and the conveyor take up length extend substantially between these two planes.